I know that if the contents of these "blocks" are indented, ST2 provides a visual indication of their "scope" and the ability to fold them by clicking an icon next to the line number. I'm looking for a keyboard shortcut and the ability to go from start to end or end to start, like CTRL+M. In this case, it's probably good enough if there's an implementation that relies on indentation, and I imagine it would be much harder to implement something like this without relying on indentation.

2) Do the equivalent for HTML start / end tags (i.e. keyboard shortcut to jump from start tag to end tag and vice versa), without relying on indentation? In a search, I found a thread where someone asked about this in December, and I see the response says there's no functionality for it in ST2, so I guess it would have to be a plugin for this one.